Hi! I have a 2011 MBP 8,1 and I just ran the Apple Hardware Test and one error code was shown: 4SNS/1/40000001:VP0R-0.057 Does anyone know what that could mean? I think it may have something to do with my power source as I can only really use the computer while it's plugged in, when it is using only the battery for power everything lags BAD, like not usable. I even replaced the battery and the magsafe 'port' and I'm still having problems. Any help is appreciated